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diff --git a/admin/unidata/emoji-zwj.awk b/admin/unidata/emoji-zwj.awk
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+++ b/admin/unidata/emoji-zwj.awk
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+#!/usr/bin/awk -f
+
+## Copyright (C) 2020 Free Software Foundation, Inc.
+
+## Author: Robert Pluim <rpluim@gmail.com>
+
+## This file is part of GNU Emacs.
+
+## GNU Emacs is free software: you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation, either version 3 of the License, or
+## (at your option) any later version.
+
+## GNU Emacs is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+
+## You should have received a copy of the GNU General Public License
+## along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
+
+### Commentary:
+
+## This script takes as input Unicode's emoji-zwj-sequences.txt
+## and produces output for Emacs's lisp/international/emoji-zwj.el.
+## It also outputs the composition sequences for flags, UK flags, and
+## skin tones which have been derived from emoji-sequences.txt by hand.
+
+## For additional details, see <https://debbugs.gnu.org/39799#8>.
+
+## Things to do after installing a new version of
+## emoji-zwj-sequences.txt and emoji-sequences.txt
+## Check the output against the old output.  See if there are any new
+## composition sequences in emoji-sequences.txt that that need to be
+## added Rebuild emacs, visit emoji-zwj-sequences.txt and
+## emoji-sequences.txt and check that the various sequences are being
+## composed properly.  Don't forget to install an appropriate font,
+## such as Noto Color Emoji.
+
+### Code:
+
+/^[0-9A-F].*; RGI_Emoji_(ZWJ|Modifier)_Sequence/ {
+    sub(/ *;.*/, "", $0)
+    num = split($0, elts)
+    if (ch[elts[1]] == "")
+    {
+        vec[elts[1]] = ""
+        ch[elts[1]] = elts[1]
+    }
+     else
+     {
+         vec[elts[1]] = vec[elts[1]] "\n"
+     }
+     vec[elts[1]] = vec[elts[1]] "\""
+    for (j = 1; j <= num; j++)
+    {
+        c = sprintf("\\N{U+%s}", elts[j])
+        vec[elts[1]] = vec[elts[1]] c
+    }
+    vec[elts[1]] = vec[elts[1]] "\""
+}
+
+END {
+     print ";;; emoji-zwj.el --- emoji zwj character composition table  -*- lexical-binding:t -*-"
+     print ";;; Automatically generated from admin/unidata/emoji-{zwj-,}sequences.txt"
+     print "(eval-when-compile (require 'regexp-opt))"
+
+     # The following codepoints are not emoji, but they are part of
+     # emoji sequences.  We have code in font.c:font_range that will
+     # try to display them with the emoji font anyway.
+
+     trigger_codepoints[1] = "261D"
+     trigger_codepoints[2] = "26F9"
+     trigger_codepoints[3] = "270C"
+     trigger_codepoints[4] = "270D"
+     trigger_codepoints[5] = "2764"
+     trigger_codepoints[6] = "1F3CB"
+     trigger_codepoints[7] = "1F3CC"
+     trigger_codepoints[8] = "1F3F3"
+     trigger_codepoints[9] = "1F3F4"
+     trigger_codepoints[10] = "1F441"
+     trigger_codepoints[11] = "1F574"
+     trigger_codepoints[12] = "1F575"
+     trigger_codepoints[13] = "1F590"
+
+     printf "(setq auto-composition-emoji-eligible-codepoints\n"
+     printf "'("
+
+     for (trig in trigger_codepoints)
+     {
+         printf("\n?\\N{U+%s}", trigger_codepoints[trig])
+     }
+     printf "\n))\n\n"
+
+     #  We add entries for 'codepoint U+FE0F' here to ensure that the
+     # code in font_range is triggered.
+
+     for (trig in trigger_codepoints)
+     {
+         codepoint = trigger_codepoints[trig]
+         c = sprintf("\\N{U+%s}", codepoint)
+         vec[codepoint] = vec[codepoint] "\n\"" c "\\N{U+FE0F}\""
+     }
+
+     print "(dolist (elt `("
+
+     for (elt in ch)
+    {
+        printf("(#x%s .\n,(eval-when-compile (regexp-opt\n'(\n%s\n))))\n", elt, vec[elt])
+    }
+     print "))"
+     print "  (set-char-table-range composition-function-table"
+     print "                        (car elt)"
+     print "                        (nconc (char-table-range composition-function-table (car elt))"
+     print "                               (list (vector (cdr elt)"
+     print "                                             0"
+     print "                                             'compose-gstring-for-graphic)))))"
+
+     print ";; The following two blocks are derived by hand from emoji-sequences.txt"
+     print ";; FIXME: add support for Emoji_Keycap_Sequence once we learn how to respect FE0F/VS-16"
+     print ";; for ASCII characters."
+
+     print ";; Flags"
+     print "(set-char-table-range composition-function-table"
+     print "                      '(#x1F1E6 . #x1F1FF)"
+     print "                      (nconc (char-table-range composition-function-table '(#x1F1E6 . #x1F1FF))"
+     print "                             (list (vector \"[\\U0001F1E6-\\U0001F1FF][\\U0001F1E6-\\U0001F1FF]\""
+     print "                                           0"
+     print "                                    'compose-gstring-for-graphic))))"
+
+     print ";; UK Flags"
+     print "(set-char-table-range composition-function-table"
+     print "                      #x1F3F4"
+     print "                      (nconc (char-table-range composition-function-table #x1F3F4)"
+     print "                             (list (vector \"\\U0001F3F4\\U000E0067\\U000E0062\\\\(?:\\U000E0065\\U000E006E\\U000E0067\\\\|\\U000E0073\\U000E0063\\U000E0074\\\\|\\U000E0077\\U000E006C\\U000E0073\\\\)\\U000E007F\""
+     print "                                           0"
+     print "                                    'compose-gstring-for-graphic))))"
+
+     printf "\n(provide 'emoji-zwj)"
+}